Cannot Uninstall .Net Framework 3.5 (pre-release version)

I'm upgrading to Orcas Beta 2 (from Beta 1) on my Vista machine.

First I must uninstall the previous installations related to Beta 1.

When I try to uninstall the .Net Framework 3.5 (pre-release version) it tells me that XP Service Pack 2 must first be installed. But I'm on a Vista machine.

Any hints?

Thanks

[377 byte] By [FrankNeubecker] at [2008-1-7]